SLVAEQ0A February 2020 – November 2020 TPS54618C-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a Failure Mode Analysis (FMA) for the pins of the TPS54618C-Q1. The failure modes covered in this document include the typical pin-by-pin failure scenarios:
- Pin short-circuited to Ground (see Table 4-2)
- Pin open-circuited (see Table 4-3)
- Pin short-circuited to an adjacent pin (see Table 4-4)
- Pin short-circuited to VIN (see Table 4-4)
Table 4-2 through Table 4-4 also indicate how these pin conditions can affect the device as per the failure effects classification in Table 4-1.
Table 4-1 TI Classification of Failure Effects
| Class | Failure Effects |
|---|---|
| A | Potential device damage that affects functionality |
| B | No device damage, but loss of functionality |
| C | No device damage, but performance degradation |
| D | No device damage, no impact to functionality or performance |
Figure 4-1 shows the TPS54618C-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the TPS54618C-Q1 data sheet.
Figure 4-1 Pin DiagramTable 4-2 Pin FMA for Device Pins Short-Circuited to
Ground
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VIN | 1 | Device does not power up, no output voltage | B |
| VIN | 2 | Device does not power up, no output voltage | B |
| GND | 3 | Normal operation | D |
| GND | 4 | Normal operation | D |
| AGND | 5 | Normal operation | D |
| VSENSE | 6 | 100% duty cycle operation, no regulated output voltage. Output voltage will follow the input voltage and go low periodically during refresh cycles of the bootstrap capacitor | B |
| COMP | 7 | 0% duty cycle operation, no output voltage | B |
| RT/CLK | 8 | Device is not switching, no output voltage | B |
| SS/TR | 9 | Device does not turn on, no output voltage | B |
| PH | 10 | Potential device damage | A |
| PH | 11 | Potential device damage | A |
| PH | 12 | Potential device damage | A |
| BOOT | 13 | Damage the VIN to BOOT path | A |
| PWRGD | 14 | PWRGD signal is always low, output voltage is regulated as programmed | B |
| EN | 15 | Device is disabled, no output voltage | B |
| VIN | 16 | Device does not power up, no output voltage | B |
Table 4-3 Pin FMA for Device Pins Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VIN | 1 | Normal operation, pins 2 and 16 are still connected | C |
| VIN | 2 | Normal operation, pins 1 and 16 are still connected | C |
| GND | 3 | Normal operation, pin 4 is still connected | C |
| GND | 4 | Normal operation, pin 3 is still connected | C |
| AGND | 5 | Normal operation, potential jitter issues | C |
| VSENSE | 6 | 100% or 0% duty cycle operation, no regulated output voltage. Output voltage will either follow the input voltage and go low periodically during refresh cycles of the bootstrap capacitor or no output voltage | B |
| COMP | 7 | No loop compensation, output voltage can oscillate | B |
| RT/CLK | 8 | Very low switching frequency operation | B |
| SS/TR | 9 | No softstart function, output voltage is regulated as programmed | C |
| PH | 10 | Normal operation, pins 11 and 12 are still connected | C |
| PH | 11 | Normal operation, pins 10 and 12 are still connected | C |
| PH | 12 | Normal operation, pins 10 and 11 are still connected | C |
| BOOT | 13 | Boot capacitor is not charged, high side switch cannot be turned on, no output voltage | B |
| PWRGD | 14 | PWRGD signal is not available, output voltage is regulated as programmed | B |
| EN | 15 | EN pin is internally pulled up, device cannot be disabled, output voltage is regulated as programmed | B |
| VIN | 16 | Normal operation, pins 1 and 2 are still connected | C |
Table 4-4 Pin FMA for Device Pins Short-Circuited to
Adjacent Pin
| Pin Name | Pin No. | Shorted to | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|---|
| VIN | 1 | 2 | Normal operation | D |
| VIN | 2 | 3 | Device does not power up, no output voltage | B |
| GND | 3 | 4 | Normal operation | D |
| GND | 4 | 5 | Normal operation | D |
| AGND | 5 | 6 | 100% duty cycle operation, no regulated output voltage. Output voltage will follow the input voltage and go low periodically during refresh cycles of the bootstrap capacitor | B |
| VSENSE | 6 | 7 | No loop compensation, can cause output voltage oscillating. Oscillation frequency cannot be predicted. | B |
| COMP | 7 | 8 | Device will not start properly, no output voltage or too low output voltage | B |
| RT/CLK | 8 | 9 | tracking driven by RT/CLK voltage, low voltage at the output | B |
| SS/TR | 9 | 10 | Potential device damage, no output voltage | A |
| PH | 10 | 11 | Normal operation | D |
| PH | 11 | 12 | Normal operation | D |
| PH | 12 | 13 | Boot capacitor is not charged, high side switch cannot be turned on, no output voltage | B |
| BOOT | 13 | 14 | Potential device damage | A |
| PWRGD | 14 | 15 | Potential device damage | A |
| EN | 15 | 16 | If VIN > 4 V potential device damage | A |
| If VIN < 4 V device cannot be disabled, output voltage is regulated as programmed | C | |||
| VIN | 16 | 1 | Normal operation | D |
Table 4-5 Pin FMA for Device Pins
Short-Circuited to VIN
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VIN | 1 | Normal operation | D |
| VIN | 2 | Normal operation | D |
| GND | 3 | Device does not power up, no output voltage | B |
| GND | 4 | Device does not power up, no output voltage | B |
| AGND | 5 | Device does not power up, no output voltage | B |
| VSENSE | 6 | Potential device damage | A |
| COMP | 7 | Potential device damage | A |
| RT/CLK | 8 | Potential device damage | A |
| SS/TR | 9 | Potential device damage | A |
| PH | 10 | Potential device damage | A |
| PH | 11 | Potential device damage | A |
| PH | 12 | Potential device damage | A |
| BOOT | 13 | Boot capacitor is not charged, high side switch cannot be turned on, no output voltage | B |
| PWRGD | 14 | Potential device damage | A |
| EN | 15 | If VIN > 4 V potential device damage | A |
| If VIN < 4 V device cannot be disabled, output voltage is regulated as programmed | C | ||
| VIN | 16 | Normal operation | D |